Pain Assessment and Management
Assessment
Self-report is the gold standard. For patients who cannot report, use validated behavioral tools (PAINAD, FLACC, PACSLAC, DOLOPLUS-2), collateral from caregivers, and a time-limited analgesic trial. Assess total pain - physical, psychological, social, spiritual - because unrelieved total pain looks like 'drug-seeking' or 'escalating opioid need.'
Matching drug to mechanism
Nociceptive somatic and visceral pain responds to opioids, acetaminophen, NSAIDs (with renal, GI, and cardiac caution), corticosteroids, and radiation for bone metastases. Neuropathic pain responds to gabapentinoids, SNRIs such as duloxetine, tricyclics, topical lidocaine, methadone, and ketamine. Visceral pain from pancreatic cancer may respond to a celiac plexus block.
Opioid mechanics
Start short-acting, sum the 24-hour total, then convert to a long-acting agent when pain is stable. Breakthrough dose equals roughly 10%–20% of the total daily dose, offered every 1–2 hours as needed. Tolerance develops to nausea and sedation but not to constipation, so a bowel regimen is ordered prophylactically. Avoid meperidine (normeperidine seizures) and codeine in children and CYP2D6 ultrarapid metabolizers. In renal failure, morphine's M6G accumulates - prefer fentanyl.
Traps
- Equianalgesic tables assume incomplete cross-tolerance; reduce the new opioid by 25%–50% when rotating.
- Respiratory depression is rare when titrating to comfort; sedation precedes it.
- Naloxone is diluted and titrated for life-threatening hypoventilation, not given as a routine reversal.
- New diffuse pain with myoclonus may be opioid-induced hyperalgesia or neurotoxicity - rotate, don't escalate.
Rule of thumb. A patient needing three or more breakthrough doses a day needs a baseline increase, not more rescues.